My screen has turned off and I can't see anything! (Inspiron 1525)

just recently, my display monitor on my Dell Inspiron 1525 would not work anymore. I was just plugging in my regular USB on it, and opened up the pendrive shortcut (I knew it was a virus, but didn't care less about it at the time) and when I clicked on a file, my display went off, when I tried to restart the laptop, it could not work.

But upon further examination, I found out that the LCD panels were still working and showing graphics (after I shone a flashlight at the monitor), but the backlight wont work, I plugged this in an external monitor and the graphics were still fine, so I ruled it out as a videocard problem. I was thinking a virus could have changed the system files and disabled the backlight of my laptop. Thanks.